New replacement Netaheat profile pcb not working?

What is the problem my new replacement pcb will now not work without me banging or jolting it then it sparks up and ignites continuously until the next period it is called for either next day or morning also with programmer water on only heating comes on understand this may be the two port valve or mid position valve and thirdly could it be a problem with the room stat which is located in a cold hallway would appreciate feed back I can deal with most but need direction most importantly getting the boiler to come on automatically thank you part no replaced 407677

Mark
October 2012